Improvement in the manufacture of steel



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TH OMAS S. BLAIR, OF PITTSBURG, PE NNSYLVAN IA Lam s Patent No. 85,053,dated December 22, 1868.

The Schedule referred to in these Letters Patent and making part ofthe-same.

To all whom it may concern Be it known that I, THOMAS S. BLAIR, of thecity of Pittsburg, in the county of Allegheny, and State ofPennsylvania, have invented a new and useful Improvement in theManufacture of Steel; and I do hereby declare the following to be afull, clear, and exact description thereof.

My invention relates to the manufacture of steel by means of the newarticle known as pig-bloom or pig-scrap, according to the manner inwhich it is produced by the process invented byEllershausen, Guzman, andStayner, and' recently patented or about to be patented by them.

Pig-bloom or pig-scrap, so called by the inventors, consists of aconglomerate of cast-iron and an oxide or oxides, (usually the oxide ofiron,) intimately mixed together, while one of the ingredients,(cast-iron or ore) is fluid, and the other is solid, so 'as to form atonce in the mixing a somewhat loose-textured yet solid (as distinguishedfrom fluid) mass.

I need not here detail the process or method of making the pig-bloom orpig-scrap, as it is particularly described in the patent before referredto; but

In order to enable others skilled in the art to use my invention, I willproceed to describe the manner in which it is to be used and operated.

' In order to the'successful conduct of the process I am about todescribe, it is important that the pigbloom or pig-scrap, whichever isused, should contain such a relative proportion of cast-iron and oxideas to yield a steel of the required degree of hardness, becausedifferent qualities of cast-iron and different kinds of ore yieldin'this respect different results. I therefore first make a small amountof pig-scrap, and subject it to the process hereafter described, to testthe result, before preparing the pig-bloom or pig-scrapin largequantity.

Having-thus determined the proper formula for mixing the cast-iron andore, (or oxide,) to give the desired result, I proceed to make a large-quantity of "pig-bloom or pig-scrap for use in themaking of steel by myimproved process, taking care tohave the oxide and cast-iron mixed asintimately as possible.

.If"pig-scrap is used, which is in small pieces, of

' loose texture, it is careiully picked over, and those pieces which areseen to contain any raw cast-iron, being rejected, the residue, whencooled, is screened, so as to remove any loose ore from the mass. Thepieces are then placed in crucibles, and treated as a substitute forblistcrcd steel or wrought-iron in the manufacture of cast-steel, theprocess being conducted in similar crucibles and furnace, and in thesame manner as is practised in making crucible-steel, excepting thatpig-scrap or pig-bloom, broken up, is used instead of blister-steel orwrought-iron.

By first making a few sample ingots of steel from the pig-scrap, whichhas been carefully selected and screened, as before described, thecharacter of the resultant steel is ascertained, and any error in theproportion of ingredients -used in preparation of the pig-scrapis.corrected, in conducting the process on a larger scale, by addingcharcoal in the crucible, if the test steel-ingots are found too soft,or wroughtiron if they have proved too hard.

Instead of melting the pig-scrap in crucibles, as above described, itmay be melted down in an open furnace, in which case the pig-bloom,which is a loose, spongy mass, may be used, but, in this case, in ordertoinsure success, care must be taken, in making the pig-bloom orpig-scrap, not to have an excess of oxide, but to have such a relativeproportion of ore and cast-iron as will allow of the. mass being melted;as otherwise, the ore, being in excess, would remove the carbon, and themass would not melt by such treatment.

Another modification of my process is to take the pig-scrap orpig-bloomfl broken up into small pieces, and introduce it from time totime, in small quantities, into a bath of molten cast-iron, until thedesired degree of carbouization is attained.

In this process the pieces of pig-scrap. or pi bloom, (each of which isa conglomerate of cast-iron and ore, and some parts of which are in atransition state nearly approaching to malleable iron,) serve to dilutethe carbon of the cast-iron, and at the same timev the oxide of iron,which was mechanically imprisoned in the conglomerate, aids in theprocess of dilution.

' Thus the process of making steel ,by diluting the carbon is carried onwith both malleable iron and oxide of iron at the same time; whereas,heretofore, it has beenfound impracticable to use the oxideof iron forthis purpose, because, when free, it destroys the furnace. It may,however, be used-by my method, as

above described, with safety to the furnace, and greatly facilitates thereduction of the quantity of carbon.

Another advantage peculiar to this process is, that the materialintroduced into the cast-iron bath is of so open, porous, and spongy atexture, as to be more rapidly melted, and is, besides, in a chemicalcondition better adapted to produce the desired result than manufacturedwrought-iron.

This method also cheapens the manufacture of steel, as the process orprocesses necessary to the manufacture of wiought iron are omitted, thepig-bloom or pigscrap being used without being previously converted intomalleable iron.

Still another modification of my process is as follows:

Instead of introducing the raw pig-scrap or spongy pieces of pig-bloomdirectly into the bath of molten cast-iron, I charge it (the pieces ofpig-bloomor pig-' scrap) into a separate heating-furnace, which may besituate near 'to the furnace containing the bath of molten cast-iron. Itis there exposed to a high temperature, and allowedto remain at a whiteheat for some time, so as to sweat out the impurities, and it is thentransferred, with as little loss of heat as possible, into a bath ofmolten cast-iron, in.wl1ich it is melted more rapidlythan manufacturedwrought-iron would be, owing to the open, spongy, and loose texture of.the pig-bloom.

This method has the disadvantage of not introducing the iron-ore intothe bath, as it has become chemically incorporated with the mass,.inwhich it was before mechanically present, by reason of the heat of thefurnace,'-and hence it will be a less expeditious as well as more costlyprocess than that before described, but it will be found better suitedfor making extra qualities of steel, and for utilizing materials tooimpure for other modes of treatment.

This last-described method obviates the necessity, hitherto experiencedin the ordinary processes of steelmanufaeture, of using none but thefinest quality of materials, at the highest cost, because my treatmentremoves a much larger amount of impurities than can be removed by theprocesses heretofore employed.

The furnaces and applicances-used in my process, as described-in itsvarious modifications, may be such as are ordinarily employed in themanufacture of steel, and therefore need nofurther explanation here.

By the above-descn'bed application of pig-bloom or pig-scrap to themanufacture of steel, the operation is greatly simplified in detail, andreduced in ex- .pense.

3 Crucible-steel can be produced with great facility, the method I havedescribed giving complete control of the process. p

In the open-furnace treatment which I have described-the product of ablast-furnace can be run, at about equal cost, into cast pig or intopig-bloom and pig-scrap, and from these two articles, thus produceddirectly from the blast-fiu'nace, the steel= ingot is manufactured withonly one after-heating. I

In this specification the term wrought-iron is used to designatemalleable iron which has been worked; whereas the pig-bloom or pig-scrapused in my process, after it has. been exposed to a high heat, becomesmalleable, but is not wrought, retaining the open, spongy texture, whichwrought-iron or worked iron does not possess, and which renders the useof the "pig-bloom, either before or after it is converted into malleableiron, peculiarly adapted to the manufacture of steel in the manner Ihave above described.

Having thus described my improvement,

What I claim as my invention, and desire to secure by Letters Patent,

1. The manufacture of cast-steel in the crucible, from pig-bloom orpig-scrap, substantially as hereinbefore described.

2. The manufacture of steel by melting.-,d0wi1, in an .open furnace,pig-bloom or pig-scrap, composed of a mixtureof cast-iron and an oxideor oxides, in

such relative proportion of metal and oxide, as to give the necessaryratio between the oxygen, carbon, and iron, to produce the desiredresult, substantially as hereinbefore descn'bed.

3. The, manufacture of steel fromcast-iron, by adding to the cast-iron,in a melted state,.a conglomerate

